Fluorescent lamp which have a higher degree of efficiency and a longer operating life compared with an incandescent lamp, have been widely used as an alternative light source to replace incandescent lamp. Moreover, recently, in addition to conventionally used fluorescent lamps, electrodeless fluorescent lamps have been put to practical use and been under development. These electrodeless fluorescent lamps are also commonly known as electromagnetic induction lamps or simply induction lamps. Since induction lamps have no electrodes, they have an even higher efficiencies and longer operating life than that of conventional fluorescent lamps with electrodes and have a potential for becoming more and more widespread in the future. The induction lamps that are being sold in the market today are primarily used for lighting at locations where replacing lamps requires a high cost, such as landscape lighting, street lighting, bridge lighting, public park lighting, lighting for factories with high ceilings, etc.
In recent years, compact induction lamps (CIL) have been developed in the art that can be plugged into incandescent lamp sockets and used as if they were incandescent lamps, while retaining the advantageous characteristics of their larger counterparts such as the high efficiencies and long lifetimes. In addition, most induction lamps use solid mercury or mercury amalgam. In this form, the mercury is compounded with other metals, similar to the amalgam once widely used in dental fillings. It will not release toxic mercury vapor when exposed to room temperature and poses no threat of contamination. The use of amalgam, aside from eliminating the risk of mercury contamination is also used to regulate the mercury vapor pressure inside the lamp vessel that will ultimately affect the lamp efficiency. The amalgam can also be easily recovered in the case of lamp breakage and simpler to recycle at end of lamp life.
Discussions have been made on widely spreading compact induction lamps (CIL) having such advantageous characteristics as an alternative light source replacing incandescent lamps or even fluorescent lamps. Specifically, compact induction lamps (CIL) including a lamp bulb and a control circuit or a ballast circuit integrated as one unit have been developed in the art and expected to become widespread, which can be plugged into incandescent lamp sockets so that they can be used to replace incandescent lamps at locations where incandescent lamps have conventionally been used, such as hotels, restaurants, and houses.
However, use of compact induction lamps (CIL) for this purpose has traditionally been limited due to its limited mounting direction. Traditionally, compact induction lamps (CIL) need to be installed with the base down. If operated in an inverted, base up orientation, there is a great concern that the heat generated by the lamp bulb will rise. As a result, the temperature within the housing rises, heating the bulb's base containing the circuit and shortening the bulb's life. Furthermore, prior art compact induction lamps (CIL) place the amalgam at the base of the bulb. When the lamp is operated in a base up orientation, in certain situation, there is a risk that the amalgam could penetrate into the bulb and damage the lamp. A look into the prior arts discovered multiple patents that are similar, such as the ones disclosed in U.S. Pat. No. 6,528,953, U.S. Pat. No. 6,891,323, U.S. Pat. No. 5,650,041, and U.S. Pat. No. 5,629,584. However, none of them possesses the novelty of the instant invention.